openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/tools/perf/ui/progress.c b/tools/perf/ui/progress.c
new file mode 100644
index 000000000..99d60223c
--- /dev/null
+++ b/tools/perf/ui/progress.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include "progress.h"
+
+static void null_progress__update(struct ui_progress *p __maybe_unused)
+{
+}
+
+static struct ui_progress_ops null_progress__ops =
+{
+	.update = null_progress__update,
+};
+
+struct ui_progress_ops *ui_progress__ops = &null_progress__ops;
+
+void ui_progress__update(struct ui_progress *p, u64 adv)
+{
+	u64 last = p->curr;
+
+	p->curr += adv;
+
+	if (p->curr >= p->next) {
+		u64 nr = DIV_ROUND_UP(p->curr - last, p->step);
+
+		p->next += nr * p->step;
+		ui_progress__ops->update(p);
+	}
+}
+
+void __ui_progress__init(struct ui_progress *p, u64 total,
+			 const char *title, bool size)
+{
+	p->curr = 0;
+	p->next = p->step = total / 16 ?: 1;
+	p->total = total;
+	p->title = title;
+	p->size  = size;
+
+	if (ui_progress__ops->init)
+		ui_progress__ops->init(p);
+}
+
+void ui_progress__finish(void)
+{
+	if (ui_progress__ops->finish)
+		ui_progress__ops->finish();
+}